Latch arrangement for appliance

ABSTRACT

A latch arrangement for a dishwasher door in which the engaging faces of the pivotal bolt mounted on the door, and the strike mounted on the tub, have arcs which are related in a fashion that during that portion of the latching in which significant resistance to compression of the door gasket occurs, the gasket compressing force has a generally front-to-rear direction to prevent undue shifting of the door in a misaligning direction as the gasket is compressed.

United States Patent 1191 Hancock LATCH ARRANGEMENT FOR APPLIANCE [75]Inventor: Charlie L. Hancock, Grove City,

Ohio 4 [73] Assignee: Westinghouse Electric Corporation,

Pittsburgh, Pa.

[22] Filed: June 16, 1971 211 Appl. No.: 153,498

[52] US. Cl. 292/241, 292/DlG. 69 [51] Int. Cl. E05c 3/04 [58] Field ofSearch 292/240, 241, 242,

[56] f 1 References Cited UNlTED STATES PATENTS 10/1961 Jellies 292/DIG.69 6/1926 Csiga' 292/241 X 3/1899 Brachhausen n 292/241 11/1958 Bennett292/240 [451 July 17, 1973 FOREIGN PATENTS OR APPLICATIONS 519,4113/1940 Great Britain 292/241 Primary Examiner-Richard E. Moore Attorney-F. H. Henson and E. C. Arenz [57] 7 ABSTRACT A latch arrangement for adishwasher door in which the engaging faces .of the pivotal bolt mountedon the door, and the strike mounted on the tub, have arcs which arerelated in a fashion that during that portion of the latching in whichsignificant resistance to compression of the door gasket occurs, thegasket compressing force has a generally front-to-rear direction toprevent undue shifting of the door in a misaligning direction as thegasket is compressed. v

7 Claims, 5 Drawing Figures 1 LATCH ARRANGEMENT FOR APPLIANCE CROSSREFERENCE TO RELATED APPLICATION My U.S. Pat. application Ser. No.140,529, new U.S. Pat. No. 3,684,343 is related.

BACKGROUND OF THE INVENTION 1. Field of the Invention This inventionpertains to the art of latching arrangements for appliance doors, andparticularly to those arrangements in which a gasket is compressedduring a latching operation.

2. Description of the Prior Art:

Since my invention is particularly applicable for use in latching swingdown type doors on front loading dishwashers, it will be consideredprimarily in that connection. With such doors, the hinge axis isadjacent the lower edge of the door. A sealing gasket is interposedbetween tub structure framing the access opening of the tub and a facingpart of the door. In a latching arrangement in which the latch bolt ispivoted about a vertical axis (i.e., swung from one side to another)during the period when the significant compression of the gasket occursand while the latch bolt is being pulled to the side, there is atendency to shift the door sideways dueto the resistance to compressionof the gasket coupled with the lines of force between the contactingfaces of the latch bolt and the latch strike, taken with the sidewaysforce applied by the operator of the latch. Accordingly, arrangementshave been provided to avoid this problem such as mechanisms havingcompound rotational and linear movement so. that in a given point in thelatch operation, the latching force is in. a substantially front-to-reardirection to pull the door up tightly. One example of such anarrangement is found in U.S. Pat. No. 3,005,065.

Anotherproblem which must be solved in such dishwashers is to provide anarrangement in which a latch operated switch cannot be moved to itsclosed position while the dishwasher door is open. This is accomplishedin the noted patent, as well as in U.S. Pat. No. 3,377,093, by alock-out arrangement in which the latch bolt cannot be operated unlessthe door has been moved into a sufficiently closed position that thelock out is disengaged.

With both of the noted arrangements, the latching mechanism isrelatively complex and expensive ascontrasted to a latching arrangementaccording to my invention.

SUMMARY OF THE INVENTION In accordance with my invention, a relativelysimple, inexpensive latchingarrange'ment is provided in which the latchbolt face adapted to engage the strike face is formed of an are having acenter offset generally to the side of the pivotal axis of the latchbolt, and the strike face is formed of a plurality of arcs havingdifferent radii, and different centers located such, that as the door ispulled through that portion of its travel in which significantresistance to compression of the gasket occurs, the sliding movement ofthe bolt face along the strike face creates a gasket compressing forcehaving a generally front-to-rear direction to prevent undue shifting ofthe door in a sideways direction as the gasket is compressed.

Since with my arrangement, the door switch is tub mounted so that it isimpossible to operate the switch by operating the latch bolt when thedoor is open, no lockout arrangement is required. Accordingly, theinitial movement of a door toward its tightly closed position duringinitiallatch operation may beaccomplished by operation of the latch, asdistinguished from manually pushing the door to a minimum closedposition, since the latch operation accomplishes this initial movement.During this initial movement, since no significant compression of thegasket occurs the sideways shifting force on the door is minimal. Alsoin accordance with my invention, a Bellville washer is used to provideadequate friction at the pivoted latch bolt to prevent the latch frommoving toward an open position due to dishwasher vibration.

DRAWING DESCRIPTION FIG. 1 is a generally schematic side view of a frontopening undercounter dishwasher as installed, and with the door in itsopen position;

FIG. 2 is a plan view of the latch arrangement with the latch handle andbolt as shown in full lines corresponding to an unlatched position, andthe same as shown in dash lines corresponding to a fully latchedposition;

FIG. 3 is a plan view of the latch handle, bolt'and its supportingbracket;

FIG. 4 is an edge view of the latch handle, bolt and supporting bracket;and i FIG. 5 is a plan view of the portion of the strike including thecam face, and including details relating to the location of the centersof the different arcs forming the strike cam face and the movement ofthe door dur ing latch operation.

BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, thesomewhat schematic illustration shows a front opening, undercounterdishwasher 10 in its installed position and with the door 12 in an openposition. The door is adapted to be swung upwardly to a closed positionabout a horizontal hinge axis adjacent the lower edge of the door.Details of the hinging arrangement and counterbalance arrangement arefound in my copending U.S. Pat. application Ser. No. l 42,307, now U.S.Pat. No. 3,704,550. The latch '14 carried by the door at the center ofits edge remote from its hinged edge operates to latch the door shut incooperation with the switch assembly 16 mounted on the upper frontcenter portion of the top wall 18 of the tub. It will be noted from FIG.1 that the forward open face of the tub includes a collar portion 20which extends along opposite sides and the top of the tub and into whichthe thickness of the door 12 is received when the door is shut. On theinner face of the door, adjacent the two side edges and the topedgc, agasket 22 is provided. I

Referring to FIG. 2, the assembly l6 includes a strike plate secured ina fixed position to the collar 20 of the tub, a door switch 26 carriedby the strike plate and a switch cover 28 which holds the switch to thestrike plate. The cam face portion of the strike plate 24 is generallydesignated 30 and will be considered in some detail inconnection withFIG. 5.

The form that the latch bolt takes is best seen in FIGS. 3 and 4. Thelatch bolt is formed as a single piece which may be provided with anoperating knob 34 at the outer end of the lever portion 36. The strikeengaging hook portion is designated 38 and is turned up gensqueeze downon a Bellville washer 46 located between the head of the pin and theupper surface of the latch bolt 14.

The leading end of the hook portion 38 of the latch is provided with anangled tongue 48 disposed to engage the operating lever 50 (FIG. 2) ofthe door switch as the latch approaches its fully closed position. Thestrike engaging face 52 of the hook portion 38 is generally curved in anare having a center 54 located generally to the side of the pivotal axisof the latch bolt. With this center, it will be apparent that successivepoints along the arc of the hook portion from the leading to thetrailing edge thereof are progressively closer to the pivotal axis forthe extent of the hook portion.

Referring to FIG. 5, the cam face 30 of the strike plate is formed by anedge of a molded plastic material 56 (preferred to avoid metal-to-metalsliding contact) which encases a portion of the strike plate. The cam iscomprised of a plurality of arcs including a portion 30A which has aradius indicated by line 30A with a center at 30A"; an are 308 with aradius indicated by line 308 greater than 30A, and'a center at 303"; andan arc 30C with a radius indicated by line 30C and a center at 30C".While it may be seen in FIG. that the arcs 30A and 30B merge smoothly,the arc 30C is offset from are 308 so that an interruption 30D is formedbetween the arcs 30B and 30C. This interrupted portion serves both toprevent the latch bolt from moving from a closed toward an openposition, and also provides a sense of feel to the user of the latchwhen the bolt portion moves intoits fully closed position. It is notedthat the nominal center line of the tub and door is indicated by theline 58 which is generally aligned with the interruption 30D.

For the purpose of explaining the manner in which the latching operationoccurs, additional lines in FIG. 5 will also be identified. Lines 60,62,64, 66, and 68 indicate successive positions of the axis of the latchhandle as it is moved from a fully open to fully latched position. Point70 indicates the location of the axis of the latch handle pivot when thefirst contact is made between the engaging faces of the latch bolt andstrike cam face. Point 72 indicates the location of t e same axis afterthe latch has been turned so the is aligned with line 64. Point 74indicates the location of this same axis when the lever has been turnedto a fully latched position. It is noted that it is only during theperiod that the door moves the distance between points 72 and 74 thatany significant part of gasket compression occurs.

The following examples of radius dimensions for a dishwasher to becommercially produced are given. 30A'0.7l0 inches; 30B'0.735 inches;30C'-0.7l0 inches; and the radius of the hook portion of the latch boltis 0.849 inches. The distance of door travel between point 70 and point72 without compression of the gasket is 0.28 inches, and between points72 and 74 with significant gasket compression is 0.10 inches.

The line 60 indicates the center line axis of the latch handle at itsfully open stop position. Line 62 indicates the axis when the first partof the hook portion contacts the strike cam face A. Line 64 indicatesthe axis when the door has been moved 0.28 inches toward closed withoutgasket compression. Line 66 indicates the location of the lever axiswhen the door has been moved its full 0.38 inches of travel to a fullyclosed position. Line 68 indicates the final position of the axis of thelever with the hook portion of the latch having moved past the 30Doffset.

With the arcs as illustrated and described, during most of the gasketcompression the points of tangency between the hook portion and thestrike cam face are closely adjacent the center line 58 of the tub anddoor. This results in the force for compressing the gasket beinggenerally aligned with a front and rear direction so that the tendencyfor the door to shift sideways is prevented. While during the 0.28inches of door travel, prior to significant gasket compressionoccurring, the points of tangency are in the arc areas 30A and then theadjacent areas of the are 303, the lack of resistance to gasketcompression permits the door to simply move toward the closed positionwithout the tendency for sideways shifting. Then during the period ofsignificant gasket compression, the point of tangency between the hookportion and the cam face of the strike moves I close to and resides onthe high point of the cam registering with the center line 58 of the tuband door.

It will also be appreciated that since there is no lockout built intothe portion of the latch arrangement carried by the door, there is noneed to manually push the door to a minimum closed position to disengagesuch a lookout before the latch can be operated.

I claim as my invention:

1. In an appliance having a cabinet with an access opening, a door forclosing said opening, and gasket means interposed between said door andcabinet, a latch arrangement comprising:

a latch bolt carried by said door and havinga pivotal axis fixedrelative to said door, said latch bolt including a strike engaging faceformed of an are having a center offset generally to the side of thesaid pivotal axis in a location such that successive points along saidare from the leading to the trailing edge thereof are progressivelycloser to said pivotal axis; and 1 strike mounted on said cabinet andincluding a camming face against which said bolt face engages as saidbolt face slides therealong to pull said door to a tightly closedposition, said camming face being formed of a plurality of arcs havingdifferent radii, and centers located such that as said door is pulledthrough that portion of its travel in which significant resistance tocompression of said gasket occurs, the sliding movement of said boltface along said camming face creates a gasket compressing force having agenerally front-to-rear direction to prevent undue shifting of said doorin a sideways direction as said gasket is compressed. 2. In an applianceaccording to claim I: said strike engaging face of said bolt thatcontacts said camming face comprises a smooth curve.

3. In an applicane according to claim 1: said camming face comprises afirst are having a radius less than a successive second are, and a thirdsuccessive arc having a radius less than said second successive arc.

4. lnan appliance according to claim 3:

said camming face includes an offset formed at the juncture of saidsecond and thing arcs; and

said strike engaging face of said latch bolt is dimensioned so that saidtrailing edge traverses said offset in moving to a fully latchedposition of said latch bolt.

5. In an appliance according to claim I:

switch means carried on said cabinet and adapted to be engaged by theleading end portion of said latch bolt strike engaging face.

6. In an appliance according to claim 1:

said latch bolt is carried by said door through a mounting brackethaving a headed pivot pin attaching said bolt to said bracket; and

said pivot pin carries a compressed friction washer located between thehead of said pivot pin and said bolt.

7. In a front-opening dishwasher having a swingdown door for closing thefront opening of the dishwasher tub, and having compressible gasketmeans for sealing between the door and tub, a latch arrangementcomprising:

a latch bolt carried by the upper edge of said door for side-to-sidepivotal movement, said latch bolt having a strike engaging face in theform of a curve in which successive points therealong from the lead ingto the trailing edge thereof are successively closer to the pivotal axisof said latch bolt;

a strike mounted on said cabinet and including a camming face againstwhich said bolt face engages as said bolt face slides therealong to pullsaid door to a tightly closed position, said camming face beingsufficiently extensive in its total. length and most rearward point ofsaid camming face.

1. In an appliance having a cabinet with an access opening, a door forclosing said opening, and gasket means interposed between said door andcabinet, a latch arrangement comprising: a latch bolt carried by saiddoor and having a pivotal axis fixed relative to said door, said latchbolt including a strike engaging face formed of an arc having a centeroffset generally to the side of the said pivotal axis in a location suchthat successive points along said arc from the leading to the trailingedge thereof are progressively closer to said pivotal axis; and a strikemounted on said cabinet and including a camming face against which saidbolt face engages as said bolt face slides therealong to pull said doorto a tightly closed position, said camming face being formed of aplurality of arcs having different radii, and centers located such thatas said door is pulled through that portion of its travel in whichsignificant resistance to compression of said gasket occurs, the slidingmovement of said bolt face along said camming face creates a gasketcompressing force having a generally front-to-rear direction to preventundue shifting of said door in a sideways direction as said gasket iscompressed.
 2. In an appliance according to claim 1: said strikeengaging face of said bolt that contacts said camming face comprises asmooth curve.
 3. In an applicane according to claim 1: said camming facecomprises a first arc having a radius less than a successive second arc,and a third successive arc having a radius less than said secondsuccessive arc.
 4. In an appliance according to claim 3: said cammingface includes an offset formed at the juncture of said second and thingarcs; and said strike engaging face of said latch bolt is dimensioned sothat said trailing edge traverses said offset in moving to a fullylatched position of said latch bolt.
 5. In an appliance according toclaim 1: switch means carried on said cabinet and adapted to be engagedby the leading end portion of said latch bolt strike engaging face. 6.In an appliance according to claim 1: said latch bolt is carried by saiddoor through a mounting bracket having a headed pivot pin attaching saidbolt to said bracket; and said pivot pin carries a compressed frictionwasher located between the head of said pivot pin and said bolt.
 7. In afront-opening dishwasher having a swing-down door for closing the frontopening of the dishwasher tub, and having compressible gasket means forsealing between the door and tub, a latch arrangement comprising: alatch bolt carried by the upper edge of said door for side-to-sidepivotal movement, said latch bolt having a strike engaging face in theform of a curve in which successive points therealong from the leadingto the trailing edge thereof are successively closer to the pivotal axisof said latch bolt; a strike mounted on said cabinet and including acamming face against which said bolt face engages as said bolt faceslides therealong to pull said door to a tightly closed position, saidcamming face being sufficiently extensive in its total length andspannIng a sufficient front-to-rear distance that with said door in itsunlatched at rest position the leading edge of said bolt face will moveinto engagement with a portion of said camming face without closelyapproaching a gasket compressing condition, said camming face furtherhaving a contour including a plurality of arcs of different radii andrelated to the curve of said bolt face that throughout significantcompression of said gasket, the points of tangency between said cammingface and said bolt face are located closely adjacent the most rearwardpoint of said camming face.